Apparatuses and methods for multistage molding of lenses

ABSTRACT

Apparatuses and methods for multistage molding of contact lenses containing low oxygen permeable components or oxygen impermeable components. Components may be embedded within a contact lens by forming a device on a polymer substrate, molding a spacer onto a male mold, bonding the device to the spacer, removing the polymer substrate, and molding the remainder of the contact lens.

REFERENCE TO RELATED APPLICATIONS

The present application claims priority to U.S. patent application Ser.No. 16/675,710, filed Nov. 6, 2019, the contents of which areincorporated by reference herein in their entirety.

TECHNICAL FIELD

This invention relates to the general field of optical lenses, and morespecifically toward apparatuses and methods for multistage molding ofcontact lenses. Components may be embedded within a contact lens byforming a device on a polymer substrate, molding a spacer onto a malemold, bonding the device to the spacer, removing the polymer substrate,and molding the remainder of the contact lens.

BACKGROUND

The earliest reference to eyeborne optics is credited to LeonardoDaVinci for his envisioning of the value of placing optics on the eye.The first application was with glass scleral shells nearly 400 yearslater. The advent of plastics, particularly polymethylmethacrylate(PMMA) launched the era of corneal contact lenses wherein the materialmade contact with the cornea only. PMMA was characterized as having nogas permeability. Lenses required designs that allowed for fluidexchange behind the lens for oxygen delivery to the cornea. The decadeof the 1970's became a period of development of gas permeable rigidpolymers for corneal contact lenses. Lens designs were modified to acloser lens-eye relationship with resultant improvement of lens comfort.The modal amount of clearance and movement for non-gas permeable lensescould be decreased as the gas permeability of materials and theresultant oxygen transmissibility increased.

The wearing of contact lenses can cause physiological and evenpathological ocular changes to occur. These changes involve both ocularstructure and function, and hypoxia has been implicated in theiretiologies. Normal corneal metabolism and physiological function aremaintained only with an adequate supply of oxygen. Contact lensparameters are important in determining the oxygen tension between thecornea and the contact lens and whether or not the cornea is beingsupplied adequate amounts of oxygen during the wearing of these lenses.While wearing a rigid contact lens, there are two ways in which oxygencan be delivered to the cornea: transmission through the lens materialitself or through the pumping of tears (bulk-flow volume exchange andstirring) beneath the contact lens during blinking. Rigid contact lensescan be manufactured in a variety of designs to achieve appropriatecentration, movement, and tear exchange.

The use of ultra-high oxygen permeable materials presents a paradoxicalopportunity to increase thickness of a layer beneath a low or non-gaspermeable component to increase the equivalent oxygen percentage to thesurface of the cornea covered by the component. Conventional practice asaforementioned constructs lenses thinner to increase oxygentransmissibility since the formula for transmissibility is thepermeability divided by the thickness. If this practice were applied toa layer posterior to a low or non-gas permeable component, the oxygenpercentage beneath the component would decrease. Nine percent (9%) isestablished as the minimum for open eye or daily wearing for particularembodiments of the present invention.

There are references that disclose layered lens constructions thatinclude a cavity or chamber for retaining a component, a fluid or a gel.The oxygen permeability of the previously taught aqueous solutions issubstantially lower than that of the polymers intended for theembodiments of the present disclosure. While some of the prior artreferences have merit for delivering oxygen, the complexity offabricating lenses described by the art is far more challenging.Biocompatibility and management of the integrity of the aqueous or gelfilled cavities is also troublesome.

Reports of the inclusion of elements or components into contact lenseshave been made in recent years. These elements include filters, lightemitting diodes (LED), light sources, sensors, strain gauges,processors, sending units, wires and batteries. The reports include theuse of graphene for night vision display applications. In many cases,like the use of graphene, titanium pin-hole apertures, low gas permeablepolarizer filters, LED and organic LED (OLED) arrays, and dielectricstack filters, the respective elements or components are not gaspermeable or demonstrate low permeability. Thus, there has existed aneed for apparatuses and methods for incorporating the at least oneelement or component which has an oxygen permeability lower than thematerial of the lens body in a contact lens.

The current invention provides just such a solution with apparatuses andmethods for multistage molding of contact lenses. Components may beembedded within a contact lens by forming a device with or without apolymer substrate, molding a lens substrate polymer spacer onto a malemold, bonding the device to the spacer, removing the device polymersubstrate if present, and molding the remainder of the contact lens.

Elements are embedded within a contact lens using multiple stages ofmolding. Each stage incrementally builds up the lens to allow access forplacement and position control of the embedded elements relative to theoptical and mechanical axes, as well as relative to the front and backlens surfaces. This partial build up is performed by only creating aportion of the base curve surface in the first and second stages. Incertain embodiments, these stages do not extend beyond the optic zone.In other embodiments, these initial stages are focused on the opticzone, but may also extend beyond the optic zone. The first stage iscreated to define the base curve offset distance and allows for theembedded item to be molded onto this stage during the second stage ofmolding. This second stage partially or fully encapsulates the firststage, including the zone on the base curve surface of the lens. One ormore additional stages are used to fully encapsulate the former stagesand complete the finished lens. This process is not limited to three ormore stages, but could be expanded or reduced to any number of stages,but at least two stages.

The lens material used in each stage is selected such that interfacebonding is achieved. Particular embodiments provide for a lens materialused in each stage that is highly similar if not identical. The elementsembedded in the lens may vary in size and shape, but must be smallenough to be encapsulated in their integration stage and in the finallens. Mechanical properties and oxygen permeability of the embeddedmaterials may also vary greatly, including both rigid and flexiblecomponents that have high, low, or even no oxygen permeability.

It is an object of the current disclosure to provide an apparatus orapparatuses for multistage molding of contact lenses that include one ormore embedded components.

It is another object of the current disclosure to provide a method formultistage molding of contact lenses that include one or more embeddedcomponents.

It is a further object of the current disclosure to provide a multistageprocess for embedding components within a contact lens using a polymersubstrate.

Terms and phrases used in this document, and variations thereof, unlessotherwise expressly stated, should be construed as open ended as opposedto limiting. As examples of the foregoing: the term “including” shouldbe read as meaning “including, without limitation” or the like; the term“example” is used to provide exemplary instances of the item indiscussion, not an exhaustive or limiting list thereof; the terms “a” or“an” should be read as meaning “at least one,” “one or more” or thelike; and adjectives such as “conventional,” “traditional,” “normal,”“standard,” “known” and terms of similar meaning should not be construedas limiting the item described to a given time period or to an itemavailable as of a given time, but instead should be read to encompassconventional, traditional, normal, or standard technologies that may beavailable or known now or at any time in the future. Likewise, wherethis document refers to technologies that would be apparent or known toone of ordinary skill in the art, such technologies encompass thoseapparent or known to the skilled artisan now or at any time in thefuture. Furthermore, the use of plurals can also refer to the singular,including without limitation when a term refers to one or more of aparticular item; likewise, the use of a singular term can also includethe plural, unless the context dictates otherwise.

The presence of broadening words and phrases such as “one or more,” “atleast,” “but not limited to” or other like phrases in some instancesshall not be read to mean that the narrower case is intended or requiredin instances where such broadening phrases may be absent. Additionally,the various embodiments set forth herein are described in terms ofexemplary block diagrams, flow charts and other illustrations. As willbecome apparent to one of ordinary skill in the art after reading thisdocument, the illustrated embodiments and their various alternatives canbe implemented without confinement to the illustrated examples. Forexample, block diagrams and their accompanying description should not beconstrued as mandating a particular architecture or configuration.

There has thus been outlined, rather broadly, the more importantfeatures of the invention in order that the detailed description thereofmay be better understood, and in order that the present contribution tothe art may be better appreciated. There are additional features of theinvention that will be described hereinafter and which will also formthe subject matter of the claims appended hereto. The features listedherein and other features, aspects and advantages of the presentinvention will become better understood with reference to the followingdescription and appended claims.

As used herein, a lens material is a material that is appropriate foruse as a part of a contact lens, including without limitationpolydimethylsiloxane.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are incorporated in and form a part ofthis specification, illustrate embodiments of the invention and togetherwith the description, serve to explain the principles of this invention.

FIG. 1 is a cutaway side view of a component affixed to a polymersubstrate according to selected embodiments of the current disclosure.

FIG. 2 is a cutaway side view of a male mold in a first stage of moldingoperation according to selected embodiments of the current disclosure.

FIG. 3 is a cutaway side view of a male mold in a second stage ofmolding operation according to selected embodiments of the currentdisclosure.

FIG. 4 is a cutaway side view of a male mold after the removal of apolymer substrate from an embedded device according to selectedembodiments of the current disclosure.

FIG. 5 is a cutaway side view of a male mold in a final stage of moldingoperation according to selected embodiments of the current disclosure.

FIG. 6 is a cutaway side view of an apparatus for a first stage ofmultistage molding of a contact lens according to selected embodimentsof the current disclosure.

FIG. 7 is a cutaway side view of an apparatus for multistage molding fora subsequent stage of multistage molding of a contact lens according toselected embodiments of the current disclosure.

FIG. 8 is a flowchart of a multistage molding process for a contact lensaccording to selected embodiments of the current disclosure.

DETAILED DESCRIPTION OF THE DRAWINGS

Many aspects of the invention can be better understood with thereferences made to the drawings below. The components in the drawingsare not necessarily drawn to scale. Instead, emphasis is placed uponclearly illustrating the components of the present invention. Moreover,like reference numerals designate corresponding parts through theseveral views in the drawings.

FIG. 1 is a cutaway side view of a component affixed to a polymersubstrate according to selected embodiments of the current disclosure.The component 20 is affixed or otherwise temporarily secured to apolymer substrate. In particular embodiments, the component isthermoformed with the polymer substrate and trimmed to an outer diameterof 8.50 mm, where the component has a thickness of 0.15 μm and thepolymer substrate has a thickness of 10 μm for a total thickness of10.15 μm. The component may be made up of multiple portions orsubcomponents, for example, such as an inner subcomponent 21 and anouter subcomponent 22.

FIG. 2 is a cutaway side view of a male mold after a first stage ofmolding operation according to selected embodiments of the currentdisclosure. A polydimethylsiloxane (PDMS) spacer 25 is molded onto amale mold 11. In certain embodiments the spacer 25 is 300 μm thick, withan outside diameter of 8.30 mm.

FIG. 3 is a cutaway side view of a male mold in a second stage ofmolding operation according to selected embodiments of the currentdisclosure. The component 20 (which is secured to the polymer substrate15) is bonded to the spacer 25 during the second stage of the moldingoperation. Insert 31 is placed between the male mold 11 and component20, and next to spacer 25. In certain embodiments, the outside diameterof the component is greater than the outside diameter of the spacer andequal to the inside diameter of Insert 31. The lens material fills thedifference between the outside diameter of the component and the outsidediameter of the spacer. Thereby, the outside diameter of the componentis directly positioned by Insert 31. In other embodiments, the outsidediameter of the component is equal to or less than the outside diameterof the spacer. The resulting object after the second stage of themolding operation, according to selected embodiments, has an outerdiameter of 8.50 mm, with a thickness of 330 μm.

FIG. 4 is a cutaway side view of a male mold after the removal of apolymer substrate from an embedded device according to selectedembodiments of the current disclosure. With the polymer substrateremoved, there remains the component 20 bonded to the spacer 25 andinsert 31. The outer diameter remains unchanged, but the thickness isreduced by the thickness of the polymer substrate. Thus, certainembodiments provide for a total thickness of 310 μm after the removal ofthe polymer substrate, which includes the spacer with a thickness of 300μm, the component, and the bond line with a thickness of 10 μm.

FIG. 5 is a cutaway side view of a male mold after a final stage ofmolding operation according to selected embodiments of the currentdisclosure. Additional lens material 27 is molded around the component20, spacer 25, and insert 31. The lens material 27 extends beyond theouter diameter of the component 20, spacer 25, and insert 31. A femalemold may be used to form the outer surface of the lens material 27.Certain embodiments provide for a center lens thickness of 400 μm. Oncethe lens material is set, the resulting contact lens with embeddedcomponents may be removed from the mold.

FIG. 6 is a cutaway side view of an apparatus for a first stage ofmultistage molding of a contact lens according to selected embodimentsof the current disclosure. A female mold insert 41 rests within ahousing 43, supported by a compression spring 45. A male mold 44 mateswith the female mold insert 41 that provides for a cavity with an 8.30mm outer diameter, with a thickness of 300 μm. Grooves 46 in the bottomof the female mold insert 41 provide for identification of the type offemale mold insert such that it is less easily confused with othersimilar size and shaped female mold inserts, such as the second femalemold insert discussed below with reference to FIG. 7. This image depictsthe components in a first assembled position prior to closure andclamping for polymerization of the spacer material.

FIG. 7 is a cutaway side view of an apparatus for multistage molding fora subsequent stage of multistage molding of a contact lens according toselected embodiments of the current disclosure. A second female moldinsert 42 rests within a housing 43, supported by a wave washer 45. Amale mold 44 mates with the female mold insert 42 that provides for acavity with an 8.50 mm outer diameter, with a thickness of 330 μm.Grooves 46 in the bottom of the female mold insert 42 provide foridentification of the type of female mold insert such that it is lesseasily confused with other similar size and shaped female mold inserts,such as the female mold insert discussed above with reference to FIG. 6.This image depicts the components in a first assembled position prior toclosure and clamping for polymerization of the spacer material.

Furthermore, while it may be possible to use the first female moldinsert and second female mold insert with the same housing, it isnonetheless possible and in certain embodiments may be preferable tohave two same or similar housings, one to house the first female moldinsert and one to house the second female mold insert.

FIG. 8 is a flowchart of a multistage molding process for a contact lensaccording to selected embodiments of the current disclosure. Thecomponent or components are formed on a polymer substrate 81. This mayinclude trimming the component(s) and substrate to a desired outerdiameter. A spacer is molded to a male mold 82 during the first stage.While it is anticipated that the component is formed 81 before thespacer is molded to the male mold 82, it is nonetheless possible and tomold the spacer to the male mold 82 before forming the component(s) onthe polymer substrate 81. In either event, the second stage of themolding process includes bonding the components to the spacer 83. Afterbonding the components to the spacer 83, the polymer substrate isremoved 84. Finally, in the third (or subsequent) stage, the lens iscompleted by providing additional lens material to form the final shapeof the lens 85. While the step of forming the final shape of the lensmay be done in a single stage, it is also possible that the final shapeof the lens is formed using one or more additional lens materials overmultiple steps or stages.

According to certain embodiments disclosed herein, the inserts arerigid, relatively inflexible molds. However, alternative embodiments ofthe current disclosure include soft, flexible molds. The use of soft,relatively flexible molds may be used to adapt to non-spherical malemolds, such as those used to create lenses with cylinder power, as wellas to potentially allow for a more effective de-molding operation.

For example, two methods are possible when removing the molded material:direct axial separation and edge lifted separation. Direct axial methodsare harder to execute because they require the entire mold to opensimultaneously, which often results in a suction effect. The suctioneffect may be detrimental to allowing the cast material to remain on thebase mold surface. Edge lifting methods are similar, but are gentler asthey allow for one side to open and relieve suction while the balance ofthe mold remains attached. Additional rotation of the insert results inmore detachment from the cast material in a progressive peel separation.However, an edge lifting method still imparts a fairly high suctionlifting force until the inception of the seal break to relieve thesuction, and continues to add high risk during mold opening.

With a soft insert, the suction zone can be reduced or nearly eliminatedby local deformation of the insert right at the edge of the castmaterial to force the seal to break and initiate the peel process formold opening. Subsequent peeling of the soft insert continues to advancethe peel zone as it progresses across the cast material withoutimparting a suction force on the balance of the cast material that isnot yet exposed.

Certain methods of the current disclosure promote adhesion to specificmold surfaces to gain advantages during de-molding. One such methodintentionally interferes with polymerization on one surface, while notinterfering or even enhancing the polymerization on alternate moldsurface(s).

The most common methods of manipulating preferential adhesion includemethods of surface modification to increase or decrease bond surfaceadhesion. In some cases, the surface modification is a plasma energyactivation mechanism, and in other cases it involves the pre-applicationof primers (promotion) or release agents (interference) to a moldsurface to alter the strength of the bond between the mold surface andfully polymerized material being cured.

Another possible method may be implemented where a specific alterationmechanism on the surface of the mold is applied to interfere withpolymerization at the surface to a controlled depth into the castmaterial. The results of this cure inhibition could be to eitherincrease adhesion or decrease adhesion at that boundary such that castmaterial would remain connected to a desired mold surface. A furtherbenefit of this method would be enhanced adhesion of the subsequentlayer at this inhibited boundary. As a result of not fully polymerizing,there are partially completed polymer chains that are at the surfacewaiting for more monomer and activator to complete the polymerization.When a subsequent layer is applied and cured, the inhibited zone isproperly finalized (polymerized) by exposure to newly deliveredactivator to overcome the deactivated activator from the prior round ofcure.

Certain embodiments of the current disclosure describe the lens to bebuilt from back to front, as shown in FIGS. 1-5. Nonetheless, as will beappreciated by those skilled in the art after reading this disclosure,alternative embodiments of the current disclosure include building thelens from front to back. In other words, the molding process may beinverted such that the first stage is on the female mold, and theinsert(s) are designed to mate or seal to the female mold.

The apparatuses and methods disclosed herein include embeddingcomponents that are to be placed at a desired distance form a finishedlens surface, for example, the anterior or posterior surface of afinished lens. Moreover, the instant disclosure should not be limited touses of components having a polymer layer that is removed after beingcast or adhered to a lens material. Certain components that are to beembedded within a contact lens may not have any layers that are to beremoved during the fabrication process. For example, the step(s)described in FIG. 4 may be omitted, where the device 20 is not affixedto a polymer substrate 15 when bonded to the PDMS spacer as shown inFIG. 3. Accordingly, while the methods described herein may allow forthe removal of a layer from the component during the fabricationprocess, such step may not be necessary in particular embodiments.

Components are shown placed in the geometric center of the male orfemale mold. However, displacement of the components from the geometriccenter is possible, and may in some instances be desirable. Certainembodiments displace the insert from the center of the mold to which itis applied. In other embodiments, the component may be displaced in asecond stage on an otherwise geometric centered first stage curedmaterial. For example, methods according to selected embodiments of thecurrent disclosure either displace the insert of the first stage andsecond stage to achieve a displaced component; or, center the firststage and displace the component when it is placed on the cured firststage. Such methods may be used to achieve a displaced or de-centeredcomponent relative to the geometric center of the molds and/or resultingfinished lens. Additionally, the wave washer may be rotationallyasymmetric to allow for the decentration of the insert and resultantspacer.

Certain embodiments of the current disclosure includepolydimethylsiloxane, however, other materials may be implemented forother embodiments, such as low expansion silicone hydrogels or lowexpansion hydrogels.

While various embodiments of the present invention have been describedabove, it should be understood that they have been presented by way ofexample only, and not of limitation. Likewise, the various diagrams maydepict an example architectural or other configuration for theinvention, which is provided to aid in understanding the features andfunctionality that can be included in the invention. The invention isnot restricted to the illustrated example architectures orconfigurations, but the desired features can be implemented using avariety of alternative architectures and configurations.

Indeed, it will be apparent to one of skill in the art how alternativefunctional configurations can be implemented to implement the desiredfeatures of the present invention. Additionally, with regard to flowdiagrams, operational descriptions and method claims, the order in whichthe steps are presented herein shall not mandate that variousembodiments be implemented to perform the recited functionality in thesame order unless the context dictates otherwise.

Although the invention is described above in terms of various exemplaryembodiments and implementations, it should be understood that thevarious features, aspects and functionality described in one or more ofthe individual embodiments are not limited in their applicability to theparticular embodiment with which they are described, but instead can beapplied, alone or in various combinations, to one or more of the otherembodiments of the invention, whether or not such embodiments aredescribed and whether or not such features are presented as being a partof a described embodiment. Thus, the breadth and scope of the presentinvention should not be limited by any of the above-described exemplaryembodiments.

What is claimed is:
 1. A method of forming a contact lens, the methodcomprising: providing a component; providing an insert; forming a spacerby molding the component and insert together in a single first moldingstage; and forming a lens body around the component, the insert, and thespacer in a second molding stage.
 2. The method of claim 1, wherein theinsert comprises polydimethylsiloxane or a low expansion hydrogel. 3.The method of claim 1, wherein the spacer comprises polydimethylsiloxaneor a low expansion hydrogel.
 4. The method of claim 1, wherein the lensbody comprises polydimethylsiloxane or a low expansion hydrogel.
 5. Themethod of claim 1, wherein the lens body has an outer diameter, whereinthe outer diameter of the lens body is equal to or greater than theouter diameter of the component.
 6. The method of claim 1, wherein thelens body consists of the same material as the insert.
 7. The method ofclaim 1, wherein the lens body consists of the same material as thespacer.
 8. The method of claim 1, wherein the component comprisesmultiple subcomponents.
 9. The method of claim 1, wherein the lens bodyis formed around the component, the insert, and spacer between a malemold and a female mold.
 10. The method of claim 1, wherein the componentor at least one subcomponent of the component is lower in oxygenpermeability than the lens body around the component.
 11. A method forforming a contact lens, the method comprising: providing a component;providing an insert; forming a spacer by molding the component andinsert together between a male mold and a female mold insert in a singlefirst molding stage; and forming a lens body around the component, theinsert, and the spacer between the male mold and a female mold in asecond molding stage.
 12. The method of claim 11, wherein the femalemold insert is soft.
 13. The method of claim 11, wherein the female moldinsert and the female mold each have an inner diameter, wherein theinner diameter of the female mold insert is less than the inner diameterof the female mold.
 14. The method of claim 11, wherein the insertcomprises polydimethylsiloxane or a low expansion hydrogel.
 15. Themethod of claim 11, wherein the spacer comprises polydimethylsiloxane ora low expansion hydrogel.
 16. The method of claim 11, wherein the lensbody comprises polydimethylsiloxane or a low expansion hydrogel.
 17. Themethod of claim 11, wherein the lens body has an outer diameter, whereinthe outer diameter of the lens body is equal to or greater than theouter diameter of the component.
 18. The method of claim 11, wherein thelens body consists of the same material as the insert.
 19. The method ofclaim 11, wherein the lens body consists of the same material as thespacer.
 20. The method of claim 11, wherein the component comprisesmultiple subcomponents.
 21. The method of claim 11, wherein the lensbody is formed around the component, the insert, and spacer between amale mold and a female mold.
 22. The method of claim 11, wherein thecomponent or at least one subcomponent of the component is lower inoxygen permeability than the lens body around the component.